Encoding and decoding systems and methods for MPEG and other block-based video bit-stream data are now widely known. One property of video is that for any given block of pixels (e.g. macroblock) in the video frame, there is a high correlation to neighboring blocks. Video compression technologies take advantage of this through the use of prediction. When the video is encoded, the encoder predicts block properties based on neighboring blocks and then encodes the difference (residual) from the prediction. The video decoder computes the same prediction and adds the residual to the prediction to decompress the video. Since only residuals to the predictions are sent, the amount of information sent between the encoder and the decoder is compressed. One drawback to having block properties predicted based off neighboring blocks is that if a neighboring block contains an error, for example due to interference during a broadcast or errors due to color saturation and light gradation, then all subsequent blocks will also contain an error, thereby causing an entire frame of video to be corrupted.
Another property of MPEG video that allows it to be compressed is that high frequency information can be discarded without the human vision system detecting a noticeable change in the results. Video compression standards take advantage of this property by a method called quantization. The quantization is set for a particular title during the encoding process. To do this, encoding parameters are determined for that title, and the encoding parameters are set for the entire encoding for that title.
Some titles respond differently to encoding quantization settings depending on the nature of the content. The most difficult section of the video clip or the most difficult title on the recording (that is, the content that requires the highest levels of quantization) is often the limiting factor for setting the encoding. That is to say, the entire title is encoded according to the necessary encoding requirements for the most difficult portion of that title. Accordingly, even if a majority of the title does not require the high number of bits that a higher-end encoding configuration requires, the entire title has been encoded with that setting to accommodate the few portions that do require that setting.